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Life line

From the annual meeting of the American Association for the Advancement of Science in San Francisco

Umbilical cord blood could be an excellent source of stem cells to treat stroke, says a US team. The cells may also be useful in treating other diseases including Parkinson’s and Huntington’s.

Paul Sandberg and his team at the University of South Florida coaxed stem cells from human umbilical cord blood to become immature nerve cells.

When they injected these cells into the veins of rats that had suffered strokes, the results were spectacular. Within two weeks, the treated rats were performing almost as well on neurological tests as healthy rats, Sandberg says.

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The team were surprised to find that umbilical cord stem cells that had not transformed into nerve cells before injection could still migrate to the damaged area and became brain cells.

Easy harvest

Sandberg has already used stem cells from bone marrow to treat stroke in animals. In those experiments, the immature nerve cells were injected directly into the brain. He says the umbilical cells performed “at least as well as the bone marrow cells, but there are lots of advantages to using cells from umbilical cord blood.”

The blood is in abundant supply and can be frozen for long term storage. The cells are also easy to harvest from the blood. Furthermore, the young cells are unlikely to provoke an immune response in the patient, meaning a patient would not need cells preserved from their own umbilical cord for treatment.

Sandberg hopes clinical trials on humans could begin within two years. He thinks cells from one umbilical cord could be sufficient to treat a stroke in a human.

Growth factor

The team treated the blood stem cells with chemicals including neural growth factor, which induced them to transform into immature nerve cells.

They induced strokes in 60 rats, then injected about three million of the cells into a vein in each rat’s tail. Injections given 24 hours after the stroke were much more effective than injections after seven days, says Sandberg.

“Within 14 days, the animals treated within 24 hours were performing on average within 80 per cent of normal levels,” he says. “The untreated animals were performing within about 20 per cent of normal levels.”

Shortly after a stroke, there is a temporary disruption to the blood-brain barrier, which can allow cells injected into the vein to enter the brain. Sandberg thinks this is one reason why injections after 24 hours worked best.

Chemical attraction

Signals produced by the brain after damage also appear to peak after 24 hours, he says. He thinks the stem cells and immature nerve cells are attracted to these signals. But the immature brain cells were the most effective treatment in the rats, says Sandberg.

The team also found that not only did the cells migrate to the damaged part of the brain, but they prompted the brain’s own stem cells to transform into brain cells, which boosted the repair.

More research is now needed to establish the ideal number of cells and injections, Sandberg says.